320 Reviews—Lapworth and Page’s Geology. 
old fossils are removed and their places taken by others of more 
value in the present state of science. Professor Nicholson has lent 
some of the beautiful drawings from his Paleontology, such as 
Mosasaurus, Dicynodon, Hesperornis, and Odontopteryx (whose arti- 
ficial teeth, as a lady student once called them, are well shown), and 
some of the older pictures like the rather blasé Pterygotus of p. 186 
look poor beside these modern rivals. 
Jn the short sketch of the objects and scope of geology enough 
elementary knowledge is imparted to enable the student to follow 
the succeeding chapter on dynamical agencies modifying the earth’s 
crust; but a great deal of space is saved in this section to be used 
later on more purely geological matters, the author rightly thinking 
that much of this will have been taught as Physiography ; we may 
illustrate the thoroughness and conciseness of this part by a single 
sentence on the formation and maintenance of waterfalls. ‘‘ Where 
a hard stratum rests upon one of a softer nature, erosion is arrested 
above and behind, while it goes on unchecked in front and below.” 
The Petrological division is almost too brief, but we notice some 
good illustrations and oblique and inosculating (loop) faults are 
defined. 
The Historical Geology of the work is not only thorough, but 
exceedingly interesting, for the author has the faculty of grasping 
the general facies of a system and presenting it to his readers as a 
whole, so that he not only gives type sections and descriptions of 
the fauna and flora, but in a few graphic touches notes their varia- 
tions in our own limited area and over the rest of the world. In . 
order to this he does not fetter himself by any single literal plan, 
but moulds his plan to his subject (this is seen in other chapters), and 
so presents some systems differently from others. ‘The Archean 
chapter is an interesting one, and the author’s views may be gleaned 
from this passage :—‘ As most of the foliated Archean rocks occur 
in areas of regional metamorphism, it may be regarded as tolerably 
certain that they owe their schistose characters to the same agency, 
and that we are not dealing in a series of such foliated rocks with 
rock systems, but with petrological complexes.” There is a curious 
passage on page 150, and one can imagine that the author felt a little 
tempted to add to his list the Dimetian, Arvonian, Lewisian, and 
Monian systems with their synonymous localities. It is, of course, 
needless to say that the hand of the master is clearly traceable through 
the Cambrian, Silurian, and Ordovician sections, and in the latter he 
has again raised the Shropshire standard for comparison. The pale- 
ontology of each system is gone into in detail, repeated stress being 
laid on the introduction, modification, and extinction of species ; 
its volcanic energy is described, and space is generally found for an 
account of the economics and scenery of the rocks and of the phases 
of Physical Geography to which each is due. Liberal space is 
allotted to the Carboniferous system, which is used as an illustration 
of the method of working out a system of rocks in its entirety. But 
we have not time to deal with each system in detail ; the advantages 
of the method of treatment, the amount of matter introduced, its 
